Similar Tricky slave, Eiron, Bomolochus
A senex amans (from Latin: "aged lover", "amorous old man") is a stock character of classical Greek and Roman comedy, medieval literature (e.g., fabliau) and drama. It is an old jealous man married to a young woman and thus often an object of mockery. He is variously ugly, impotent, puritanical, and foolish to be cuckolded by a young and handsome man. Often the term "senex amans" is applied to the very motif involving the three.
The classic example of a senex amans is Januarie (January) in the Merchant's Tale (part of the Canterbury Tales). He is nigh on 80 (a worthy age for then) and he marries and has it with a super duperdy young girl (under 18). He rapes her and is pregnant.
The senex amans is not always a one-dimensional figure presented for derision. The morality within the tale itself is somewhat ambiguous, with the corrosive irony directed at January coupled with a more generalised sympathy and understanding.